MCP Extensions — TypeScript

Extensions for the MCP (Model Context Protocol) TypeScript SDK.

Server-Side Grouping

The org.openmcptools.extensions.groups module provides an MCP extension to support hierarchical server-side grouping based upon the typescript sdk.

What's in here

The project defines a tree-based data model to organize tools, prompts, and resources into hierarchical groups — like folders inside folders.

Core model (src/Common.ts)

• Group — a tree node. Can contain other groups, tools, prompts, and resources. Each group knows its parent and computes its fully qualified name (e.g. com.example.api).
• Tool — an MCP tool. Can belong to multiple groups at once.
• Prompt — an MCP prompt with typed arguments.
• Resource — an MCP resource (URI, size, MIME type).
• Converter — generic interface to convert between the internal model and any external format.

Config (src/GroupsExtensionConfig.ts)

Extension identifier constants (org.openmcptools/groups).

Schema (src/GroupSchema.ts)

Zod schema for group validation, built on top of the MCP Typescript SDK's BaseMetadataSchema.

This javascript schema implementation is based upon this json-schema

        "Group": {
            "properties": {
                "name": {
                    "type": "string"
                },
                "parent": {
                    "$ref": "#/definitions/Group",
                },
                "description": {
                    "type": "string"
                },
                "title": {
                    "type": "string"
                },
                "_meta": {
                    "additionalProperties": {},
                    "type": "object"
                }
            },
            "required": [
                "name"
            ],
            "type": "object"
        }

This schema for hierarchical grouping was initially proposed as a MCP protocol enhancement. For a discussion specifically of the 'parent' field, and it's role in hierarchical grouping, please see this and subsequent postings.

The same schema is used for the mcp_extensions_java group extension (Java SDK) and the mcp_extensions_python group extension (Python SDK)

How to test

cd org.openmcptools.extensions.groups
npm install
npm test

Tests cover both happy paths (creation, hierarchy, relationships) and failure scenarios (invalid names, duplicate removals, re-additions, state consistency).

Known Projects Using Extension

If you are using an extension and would like to be added to this list, please open a pr.

mcp-fusion